For many years orthopedic surgeons and other specialists have long worked with Plaster of Paris, almost exclusively, in the preparation of surgical casts. The problems associated with Plaster of Paris as to weight, water damage, x-ray opaqueness, etc. are well documented. Recently, Plaster of Paris has to a large extent been replaced with the development of orthopedic bandages which utilize cast forming compositions and mixtures using water soluble vinyl monomers such as those selected from the group consisting of diacetone acrylamide (DAA), N-isopropylacrylamide (N-IPA) and mixtures thereof wherein the monomers are polymerizable in the presence of water by means of an amine catalyst or a redox catalyst system that comprises an oxidation component and a reducing agent. Such an orthopedic bandage is described in U.S. Pat. No. 3,630,194. The bandages are hardened in a manner similar to the Plaster of Paris bandages by dipping the bandage into tap water which is then formed about the portion of the body to be immobilized or supported. Other prior art orthopedic bandages are found in U.S. Pat. Nos. 4,411,262; 4,376,438; 4,344,423; 4,502,479; and 4,433,680. The resulting hardened bandage has always been of a natural (white) color which is subject to discoloration becoming unsightly and without any fashionable character. The addition of a colorant to the cast material must take into due consideration the effect of the colorant to the cast forming material, its reactiveness, its strength, its shelf life, and possible reaction to the patient. Also, the formation of a homogeneous solution of the polymer must consider the chemical effects involved so as not to radically change the composition or the reactions involved.
The prepolymer treated bandage is soaked in water prior to application to the body member, and the wet bandage is then applied to the body member. After the bandage is applied, the cast is smoothed with a gloved hand and held at certain points until it hardens. Since the resins in the bandage are quite tacky until they cure, the protective gloves worn by the cast applier tend to stick to the bandages. This is disadvantageous since it can lead to unwinding of the cast as layers of the tape pull apart from each other and the cast cannot be molded.
To alleviate the problem of "tackiness" in curable resin-coated bandages, Scholz et al proposed, in U.S. Pat. No. 4,667,661, treating such bandages with certain lubricants to reduce the kinetic coefficient of friction of such sheets to less than about 1.2. The lubricant can be comprised of (a) hydrophilic groups which are covalently bonded to the curable resin, (b) an additive which is incompatible with the curable resin, or (c) a combination of (a) and (b). As noted in the Scholz et al patent (e.g. column 11, lines 21 et seq.), the bandages treated with such lubricants become very slippery, and molding of the cast becomes easy due to the non-tacky nature of the resin. It is also noted in the Scholz et al patent (column 8, lines 45-65) that materials such as mineral oil were evaluated as lubricants and, although they did give a non-tacky and even slippery feeling to the surface of the casting tape which allowed easy application and moldability of the tape to the patient, the effect was transient. On average, Scholz et al report, such materials lasted only a day to a week, apparently due to the dissolution of the oil into the resin.
There exists a need for a bandage material with improved handling properties, i.e. one which is neither too tacky nor too slippery.